"Many, many thousands of innocent people will die," Turnbull said.

Prime Minister Malcolm Turnbull has echoed Donald Trump's fiery threat that North Korea will be destroyed if it continues to menace the U.S. and its allies.

Hours after president Trump told the U.N. the U.S. would have "no choice but to totally destroy North Korea in order to defend itself," Turnbull backed the warning on Australian breakfast television.

When asked by Sunrise host David Koch if his "gut" is telling him there will be an attack from North Korea, Turnbull responded, saying "I don't think this guy (Kim Jong Un) will commit suicide. That's the truth."

"President Trump and I have said exactly the same thing -- if he attacks the United States that is a suicide note for his regime. Now, it is a disaster because many, many thousands will die.

"Well, it will be a massive attack, you know, a massive response that will end the regime, as the President said."

Kim Hong-Ji / Reuters
U.S. soldiers take part in a combined arms collective training exercise in Pocheon, South Korea September 19, 2017.

On Tuesday Trump threatened to "totally destroy" the country of 26 million people and mocked its leader, Kim Jong Un, as a "rocket man."

"The United States has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea," Trump told the 193-member world body, sticking closely to a script.

"Rocket Man is on a suicide mission for himself and for his regime."

KCNA/Reuters
North Korean leader Kim Jong Un watches the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017.

"It was the wrong speech, at the wrong time, to the wrong audience," Wallstrom later told the BBC.

In Germany, Chancellor Angela Merkel said she would do everything in her power to ensure a diplomatic solution. "Anything else would lead to disaster," she said.

Kim Hong-Ji / Reuters
A South Korean soldier takes part in a combined arms collective training exercise in Pocheon, South Korea September 19, 2017.

U.S. Defense Secretary James Mattis, who earlier this month raised the prospect of a "massive military response" if needed, on Tuesday told Pentagon reporters that Secretary of State Rex Tillerson was working to resolve the crisis diplomatically.

Increasing pressure for a diplomatic solution came after the U.S. staged bombing drills with South Korea over the Korean peninsula, and Russia and China began naval exercises ahead of the U.N. General Assembly meeting on Tuesday.

"There is no easy way out, no easy answer, but we need to find something in between," Jens Stoltenberg says of North Korea pic.twitter.com/SVY4XSTC73

"The President's speech was about calling out this illegal behaviour and calling on the international community to continue to condemn North Korea and ensure sufficient pressure is put on North Korea so it returns to the negotiating table," she said.

Labor Foreign Affairs spokeswoman Penny Wong said North Korea was violating international law.

"It is acting provocatively, and what we do need to do is to act as one, as an international community, to place the greatest economic diplomatic and political pressure on that regime to desist from this path," Wong said.

"I agree with Julie Bishop when she says the international community must be unified in placing that pressure on North Korea, and obviously the General Assembly which is meeting this week is an opportunity for that to occur."